KR20130095371A - Manufacturing method of stacked-typed electrode assembly of novel strucure - Google Patents

Abstract

PURPOSE: A manufacturing method of an electrode assembly is able to improve the capacity and quality of a battery compared to the identical standard battery while improving the manufacturing process of a battery cell by improving the production speed of a battery. CONSTITUTION: A manufacturing method of an electrode assembly (400) with a structure in which more than two unit cells are laminated comprises (i) a process of preparing a unit cell (a) in which an electrode plate is positioned on both external sides, respectively, and a unit cell (b) in which a membrane is adhered to both external sides, respectively; (ii) a process of laminating the unit cells on a unit cell laminating part so that an anode and a cathode face each other; (iii) a process of surrounding the exterior of the unit cell laminate taken from the unit cell laminating part with a film (410); and (iv) a process of thermally contracting the film surrounding the exterior of the unit cell laminate.

Description

Manufacturing method of Stacked-Typed Electrode Assembly of Novel Strucure

The present invention relates to a method for manufacturing an electrode assembly, and more particularly, to a method for manufacturing an electrode assembly having a structure in which two or more unit cells are stacked, (i) a unit cell in which the electrode plates are positioned on both outer surfaces thereof (a) Preparing a unit cell (b) having separators attached to both outer surfaces thereof; (ii) stacking the unit cells (a, b) such that an anode and a cathode face each other in a unit cell stack; (iii) wrapping the outer surface of the unit cell stack taken from the unit cell stack with a film; And (iv) heat shrinking the film surrounding the outer surface of the unit cell stack. 2.

BACKGROUND ART [0002] In recent years, rechargeable secondary batteries have been widely used as energy sources for wireless mobile devices. In addition, the secondary battery is an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (HEV), and the like, which are proposed as solutions for air pollution of existing gasoline vehicles and diesel vehicles using fossil fuels (Plug-In HEV) and the like.

Such secondary batteries are classified into roughly cylindrical cells, rectangular cells, and pouch cells according to external and internal structural characteristics, and among them, rectangular batteries and pouch cells having a small width to length, in particular, may be stacked. It is attracting attention.

The electrode assembly of the anode / separator / cathode structure constituting the secondary battery is largely classified into a jelly-roll type (winding type) and a stack type (laminate type) depending on its structure. In the jelly-roll type electrode assembly, an electrode active material or the like is coated on a metal foil used as a current collector, dried and pressed, cut into a band shape having a desired width and length, and a cathode and an anode are diaphragm- . Such a jelly-roll type electrode assembly may be preferably used in a cylindrical battery, but in application to a square or pouch type battery, the stress is locally concentrated and the electrode active material is peeled off or the battery shrinks due to shrinkage and expansion phenomenon repeated during charge and discharge. There is a problem that causes deformation.

On the other hand, the stacked electrode assembly has a structure in which a plurality of anode and cathode unit cells are sequentially stacked, and has an advantage of easily obtaining a rectangular shape, but when the manufacturing process is complicated and an impact is applied, the electrode is pushed and a short circuit occurs. There is a disadvantage that is caused.

In order to solve this problem, in the prior art some prior art electrode assembly of the advanced structure, which is a mixed form of the jelly-roll type and stack type, a full cell or a positive electrode of a cathode / separator / cathode structure of a certain unit size ( A stack / foldable electrode assembly has been developed in which a bicell having a structure of cathode) / separator / cathode (anode) / separator / anode (cathode) is folded using a continuous separation film having a long length.

1 and 2 schematically show an exemplary manufacturing process of such a folded assembly, and FIG. 3 shows a stack / foldable electrode assembly manufactured by this manufacturing process.

Referring to these drawings, the stack / foldable electrode assembly may, for example, arrange the unit cells 10, 11, 12, 13, and 14 on the separator sheet 20 having a long length and the separator sheet 20. It is produced by winding up sequentially starting at one end 21 of.

However, internal spaces or systems for the manufacturing process are indispensable, and the process is very complicated. As a result, unit cells must be arranged in a long sheet-type separator, and unit cells and separators are folded and folded at both ends. The disadvantage is the high cost of equipment investment. Furthermore, as the unit cells increase, it is difficult to wind the unit cells arranged in a line, there is a problem that the defective rate of the electrode assembly can be increased.

Furthermore, the stack / foldable electrode assembly of FIG. 3 manufactured by the above method may cause an internal short circuit between the positive electrode tabs 31 or the negative electrode tabs 32 and the main body while the electrode assembly is pushed out when the external body is impacted. That is, when a predetermined object presses the battery by an external force, the positive electrode tabs 31 or the negative electrode tabs 32 are brought into contact with the opposite electrode of the main body, and a short circuit is caused. Will rise.

Therefore, it can be manufactured by a simple manufacturing process, even when an external force is applied to the secondary battery, there is a high necessity for a technology capable of securing the life and safety of the battery.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems of the prior art and the technical problems required from the past.

After various experiments and in-depth studies, the inventors of the present application improve the manufacturing processability by improving the production speed of the battery by manufacturing the electrode assembly in a specific manner, and improve the capacity and quality of the battery compared to the same standard. It was confirmed that the present invention was completed.

Therefore, the method of manufacturing an electrode assembly according to the present invention is a method of manufacturing an electrode assembly having a structure in which two or more unit cells are stacked.

(i) preparing a unit cell (a) having electrode plates positioned on both outer surfaces thereof, and a unit cell (b) having separators attached to both outer surfaces thereof;

(ii) stacking the unit cells (a, b) such that an anode and a cathode face each other in a unit cell stack;

(iii) wrapping the outer surface of the unit cell stack taken from the unit cell stack with a film; And

(iv) heat shrinking the film surrounding the outer surface of the unit cell stack;

Consists of a configuration that includes.

In the method of manufacturing an electrode assembly according to the present invention, the unit cells (a) having the electrode plates positioned on both outer surfaces thereof and the unit cells (b) having the separators attached to the outer surfaces of both sides thereof are stacked in a predetermined manner, and then taken out. Since the film is wrapped in a film and thermal contraction is performed, it is possible to reduce battery defects caused by the arrangement of unit cells that may occur in a conventional stack / foldable electrode assembly, thereby improving the production speed of the battery and improving manufacturing processability. While improving, the capacity and quality of the battery compared to the same standard can also be improved.

The unit cell (a) and the unit cell (b) is a structure in which two or more pole plates are stacked with a separator placed thereon, and in particular, the unit cell (a) has pole plates positioned on both outer surfaces thereof, and the unit cell. (b) is characterized in that the separation membrane is attached to each of both outer surfaces.

Therefore, the process (i) may include a process of manufacturing a unit cell (b) by laminating a separator on the outer surface of the anode of the full cell or the A-type or C-type bicell, respectively.

Specifically, the unit cell (a) is a full cell of an anode / separation membrane / cathode structure in which the outermost electrode plates on both sides form opposite electrodes to each other, and the unit cell (b) has a separator on both outer surfaces thereof. It may be an attached full cell.

In some cases, the unit cell (a) is a C-type bicell having an anode / separation membrane / cathode / separation membrane / anode structure in which the anode plates of the anode outermost electrode form the same electrode, and the unit cell (b) May be an A-type bicell having a cathode / separation membrane / anode / separation membrane / cathode structure, each having a separator attached to both outer surfaces thereof.

As another example, the unit cell (a) is an A-type bicell having a cathode / separation membrane / anode / separation membrane / cathode structure, and the unit cell (b) has an anode / separation membrane / cathode / separation membrane, each having a separator attached to both outer surfaces thereof. / C-shaped bicell of the bipolar structure.

The process (ii) may include laminating the A-type bi-cell and the C-type bi-cell in an alternating manner so that the positive electrode and the negative electrode face each other in the unit cell stacking unit. As described above, one of the A-type or C-type bicells has a structure in which separation membranes are attached to both outer surfaces thereof, so that a separate separation membrane is not required between the unit cells in the stacking process of the unit cells. Not only can the manufacturing time be shortened, but also the efficiency in the manufacturing process can be increased.

In one preferred example, the unit cell stacking portion may be a structure consisting of an upper portion of the hopper structure having an open upper end and a smaller diameter in the lower direction, and a lower portion having an inner size corresponding to the unit cell stack. Therefore, the plurality of unit cells easily collected by the upper portion may be evenly and smoothly stacked by the lower structure while moving downwardly by gravity.

In the above structure, a lower discharge port may be formed in the lower portion of the unit cell stack so that the unit cell stack may be sequentially taken out. Thus, the unit cell entire body drawn into the lower outlet can be easily wrapped by the film.

Specifically, the lower portion of the unit cell stack may be, for example, a structure having an inner diameter larger than that of the electrode plate of the unit cell and smaller than the separator. That is, when the unit cell stack moves below the unit cell stack, the separator contacts the lower inner wall and descends to a force corresponding to gravity due to the elasticity of the separator and the frictional force against the lower inner wall. Therefore, the unit cell stacks may be sequentially stacked without being physically pressed.

In addition, a step may be formed below the unit cell stack to support the separator of the unit cell. That is, when unit cell stacks are sequentially stacked, if the unit cell stacks exceed the height of the step, they are drawn into the lower outlet.

The step is not particularly limited as long as the structure easily supports the unit cell stack, and may be, for example, a structure formed at a boundary or a lower portion or a lower outlet of the upper and lower portions of the unit cell stack.

On the other hand, the through-holes for the exhaust may be perforated below the unit cell stack. Therefore, by removing the air collected between the separator of the unit cell and the lower portion of the unit cell stack that contacts the lower inner wall, the unit cell stack can be easily lowered to the lower outlet.

On the other hand, the present invention includes a process of wrapping the outer surface of the unit cell laminate taken from the unit cell stack through the above process with a film, in one preferred embodiment, the one side of the unit cell stack is wrapped in a film It may include a step of continuously wrapping the corresponding surface with a film.

The step (iv) may include a process of thermally fusion bonding the overlapping portions of the film in the state that the outer surface of the unit cell stack is wrapped with the film.

Such a film serves to protect the unit cell antagonist from the outside, and for example, a material made of polypropylene, a copolymer of polypropylene, or a blend may be used, and may have a porous structure.

In addition, such a film, since heat shrinkage can occur preferably in the range of 150 ~ 180 ℃ can support a fixed state with respect to the unit cell laminate.

The present invention also provides an electric cell manufactured using the method of manufacturing such an electrode assembly.

The battery cell may be, for example, a secondary battery or an electrochemical capacitor, and may be preferably applied in a lithium secondary battery.

As described above, the electrode assembly manufacturing method according to the present invention includes a series of processes for stacking the unit cells (a, b) in a specific manner to make a unit cell stack, take it, wrap it with a separation film and then heat shrink it. In addition, while improving the production process of the battery cell by improving the production rate of the battery can improve the capacity and quality of the battery compared to the same standard.

1 is a schematic diagram showing a manufacturing process of a stack / foldable electrode assembly composed of conventional bi-cells;
FIG. 2 is a schematic diagram illustrating an arrangement combination of bicells in the stack / folding electrode assembly of FIG. 1;
3 is a schematic diagram of the electrode assembly structure manufactured by FIG. 1;
4A and 4B are schematic diagrams of one exemplary bicell that can be preferably used as the unit cell (a) and the unit cell (b) in the electrode assembly, respectively;
5 is a schematic view of a unit cell stacking unit according to an embodiment of the present invention; And
6 is a schematic view of the electrode assembly structure according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited by the scope of the present invention.

4A and 4B, respectively, are schematic views of one exemplary bicell 100 and another bicell 200, which can be preferably used as unit cell (a), unit cell (b) in an electrode assembly. have.

Referring to FIG. 4, the unit cell 100 is a C-type bicell composed of a unit structure of an anode, a separator 130, a cathode, a separator, and an anode, and each cell has anodes positioned at both sides of the cell. The unit cell 200 is an A-type bicell having a cathode / separator / anode / separator / cathode structure, each having a separator 130 attached to both outer surfaces thereof. Since the unit cell 200 has a separator 130 attached to both outer surfaces thereof, when the unit cell 100 and the unit cell 200 are used to form an electrochemical cell including a secondary battery, a separate separation film Even if it is not disclosed, the positive electrode and the negative electrode may be stacked facing each other.

5 is a schematic diagram of a unit cell stacking unit according to an exemplary embodiment of the present invention.

Referring to FIG. 5 together with FIG. 4, the unit cell stacking unit 300 is a structure in which the unit cell 100 and the unit cell 200 are sequentially stacked by being introduced from the top in an alternating manner. It consists of an upper portion 310 of the hopper structure having a smaller diameter in the direction, and a lower portion 320 having an internal size corresponding to the unit cell stack 300.

The lower discharge port 322 is formed in the lower portion 320 of the unit cell stacking unit so that the unit cell stacks 100 and 200 formed of the unit cell 100 and the unit cell 200 may be sequentially taken out.

In addition, since the lower part 320 of the unit cell stacking part is larger than the electrode plate of the unit cell and has an inner diameter smaller than that of the separation membrane 130, the separation membrane 130 of the unit cell stacks 100 and 200 contacts the lower inner wall. Due to the elasticity and the frictional force on the lower inner wall is lowered to the force corresponding to gravity. Therefore, the unit cell stacks may be sequentially stacked without being physically pressed.

In addition, a stepped portion 324 supporting the separation membrane 130 of the unit cell is formed in the lower portion 320 and the lower outlet 322 of the unit cell stack. Therefore, when the unit cell stacks 100 and 200 are sequentially stacked, if the height of the step is exceeded, the unit discharge stacks 322 are taken out.

On the other hand, through-holes 326 for evacuation are perforated in the lower part 320 of the unit cell stack part, and the air pressure state between the separator 130 of the unit cell and the lower part 320 of the unit cell stack part which contact the inner bottom wall of the unit cell stack is formed. By eliminating the unit cell stack (100, 200) can be easily lowered to the lower outlet (322).

FIG. 6 schematically illustrates the structure of the electrode assembly 400 in which the outer surfaces of the unit cell stacks 100 and 200 taken from FIG. 5 are wrapped with a film.

5, the outer surface of the unit cell stacks 100 and 200 is surrounded by the film 410 and overlaps the film 210 on the upper surface of the unit cell stacks 100 and 200. Heat seal the site.

Each of the films 410 is made of polypropylene, a copolymer of polypropylene, or a blend of materials so as to maintain their insulation state between the electrode plates and unit cell stacks of the unit cells, respectively.

On the other hand, the unit cell stack 100, 200, the film 410 wrapped around the unit cell stack 100, 200 is preferably heat shrink at 170 ℃, the heat shrink film 410 is a unit cell stack ( It supports the fixed state with respect to 100 and 200, and functions to protect the unit cell stacks 100 and 200 from the outside.

Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims (18)

A method of manufacturing an electrode assembly having a structure in which two or more unit cells are stacked,
(i) preparing a unit cell (a) having electrode plates positioned on both outer surfaces thereof, and a unit cell (b) having separators attached to both outer surfaces thereof;
(ii) stacking the unit cells (a, b) such that an anode and a cathode face each other in a unit cell stack;
(iii) wrapping the outer surface of the unit cell stack taken from the unit cell stack with a film; And
(iv) heat shrinking the film surrounding the outer surface of the unit cell stack;
Method for producing an electrode assembly comprising a. The electrode assembly of claim 1, wherein the step (i) comprises fabricating a unit cell (b) by laminating a separator on an outer surface of the full cell or the A-type or C-type bicell, respectively. Manufacturing method. The electrode of claim 1, wherein the unit cell (a) is a full cell of a cathode / separation membrane / cathode structure, and the unit cell (b) is a full cell having separators attached to both outer surfaces thereof. Method of manufacturing the assembly. The method of claim 1, wherein the unit cell (a) is a C-type bicell of the anode / separator / cathode / separator / anode structure, the unit cell (b) is a cathode / with a separator attached to the outer surface on both sides / A method for producing an electrode assembly, characterized in that the A-type bi-cell of the membrane / anode / separator / cathode structure. The method of claim 1, wherein the unit cell (a) is an A-type bicell having a cathode / separation membrane / anode / separation membrane / cathode structure, and the unit cell (b) has an anode / separation membrane / cathode with separators on both outer surfaces thereof. Method for producing an electrode assembly, characterized in that the C-type bi-cell / separator / anode structure. The method of claim 4 or 5, wherein in the step (ii) the production of the electrode assembly, comprising the step of laminating the A-type bi-cell and the C-type bicell alternately so that the positive electrode and the negative electrode face each other Way. The electrode assembly of claim 1, wherein the unit cell stack is formed of an upper portion of a hopper structure having an open top and a smaller diameter in a lower direction, and a lower portion having an inner size corresponding to the unit cell laminate. Manufacturing method. The method of claim 7, wherein a lower discharge port is formed under the unit cell stack to allow the unit cell stack to be sequentially taken out. 8. The method of claim 7, wherein the lower portion of the unit cell stack is larger than the electrode plate of the unit cell and has an inner diameter smaller than that of the separator. The method of claim 7, wherein a step of supporting the separation membrane of the unit cell is formed under the unit cell stack. The method of claim 7, wherein the step is formed at a boundary or a lower portion or a lower outlet of the upper and lower portions of the unit cell stack. The method of claim 7, wherein the through-holes for exhausting are perforated under the unit cell stack. The method of claim 1, wherein the step (iv) comprises the step of thermal fusion bonding of the overlapping portion of the film in the state that the outer surface of the unit cell stack is wrapped with a film. The method of claim 1, wherein the film is made of polypropylene, a copolymer or blend of polypropylene. The method of claim 1, wherein the film is a porous structure film. The method of claim 1, wherein the film is heat shrinkage occurs in the range of 150 ~ 180 ℃ manufacturing method of the electrode assembly. A battery cell, which is manufactured using the manufacturing method according to any one of claims 1 to 16. 18. The battery cell according to claim 17, wherein the battery cell is a lithium secondary battery.

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